GPS marker on map

[ljbade]

I want to take whatever @bleege cooks up in https://github.com/mapbox/mapbox-android-sdk/issues/593 and https://github.com/mapbox/mapbox-android-sdk/issues/592 to implement a GPS map marker in the demo app.

[ljbade]

I changed the GPS button to toggle location updates on or off. The updates are once a second and keep the map centre updated.

I used the https://github.com/mapzen/LOST that @bleege found.

Now I need to figure out how to add a marker to the map with compass direction and accuracy circle.

@incanus I guess this would be a good use of the client-side data stuff you are working on?

[incanus]

Yes, this is exactly what that is for. You can maybe fake it at screen center for tracking for now (i.e. put the marker above the map) but that won't help when you want to pan the map while showing the user.

[ljbade]

Yeah I was thinking about faking it @incanus. To get around the scrolling issue I may calculate screen coord from the zoom level and lat/lon

[incanus]

Yeah, for a single marker, I'll bet that will work fine for now. I'll be watching as that could be useful on iOS as a stopgap too.

[ljbade]

Will need to use these conversions:
#476

[ljbade]

Related iOS ticket: #147